Motorhead Memo: Make the eagle scream

December 27, 2017

By Kip Woodring

A $19,000 Heritage Classic will run with a $40,000 CVO Road Glide. A 114” Heritage will outrun one! Huh? The bargain Tourer will smoke the flagship? How can that be?

Well, it almost always has been, because Touring bikes are heavier than cruisers. So how can it not be? Besides, since the advent of 103” Big Twin engines, most riders are satisfied with the ample power they have. The Milwaukee-Eight (in all displacements) just increases the percentages. If you are in this group, you might want to turn to some other page of interests more aligned with your priorities. For those who believe there’s no such thing as enough power please feel free to keep reading. Oh, it might be handy to have access to information on M-8 Screamin’ Eagle parts too. It’s all in the 2018 GMA catalog, and you can download it from Harley’s website. I’ll wait here.

Ready? OK… let’s begin with this; Harley’s Touring CVO Big Twin’s are often referred to (almost interchangeably) as “Screamin’ Eagle.” We (and they) need to stop that! Unless CVO models start coming with Stage IV stuff from the factory… it just ain’t so! Real SE parts are always added to and never delivered on any H-D. Henceforth—better to stick with CVO as the correct reference, because “custom” vehicle operations is all they are.

Case in point (and as good a place as any to start) is the 95 hp CVO 117” engine as applied to 2018 Touring models. (But not Softails!) For the record, the only thing special about these engines, relative to their smaller brethren, is displacement and misleading SE labeling. The cams are the same as any other production M-8. The heads too. Stroke is the same as the stock 114” engines. All that’s really different is the air cleaner, the pipes and the bore. A pretty tame engine “tune” overall. Now, whip to page 589 (figure 1). Lo and behold! We see Stage IV kits for the M-8. Look closely at what’s included. Notably, heads, throttle body, and a cam that weren’t there in last year’s Stage 3 kit. Not one bit of it is stock/standard on a CVO 117” because this is “real” Screamin’ Eagle stuff!

Care to take a glance at the somewhat confusing power/torque charts on pages 572 and (figure 2) 573? They show the potential of SE “stages.” For now let’s just explore the Stage IV 117” kit(s) and all the peripherals that go with it… starting with the fine print that appears at the bottom of the charts. To get the results you see graphed, you must purchase a bit more than just the kit. (But you already knew that, right?) All the same, besides the kit, the additional item most critical to success is the “high flow” exhaust shown (figure 3) on pages 582–583. (One can’t help but wonder if more efficiency might be had from that head pipe setup… without cats in the mufflers. Discuss?) Anyway, for now, there’s no way to get 120-plus hp and 115 ft/lbs of torque without it. Just look at charts of the same kit applied to Softails with “Street Cannon” exhaust to see the difference. You want that 117” bagger to outrun a Softail, you’ll need to pony up (in both senses) for the STG IV kit, the pipe, the tuner(s), a performance air cleaner, cam drive retention kit, cam spacer kit and most likely 10–14 hours of labor. T’ain’t cheap horsepower. Here’s some math in round numbers;

SE Stage IV kit = $2,600

High Flow exhaust = $1,300–$1,400

Pro Street Tuner = $300

Cable for Tuner = $30

Smart Tune Pro Automatic Tuning Module = $400

Air Cleaner = $300–$600 (or more, with trim)

Cam Retention kit + Cam Spacer kit = $16

Total—approximately $5,000–$5,400

Figure 2

Labor varies (to put it mildly) but here again, for easy figuring let’s just say $100 per hour at a franchised dealer. So, the “ballpark” for attaining the magic Screamin’ Eagle 120 hp 117” “Softail beater” would amount to something between $6,400–$6,800. That’s like $250 per pony! (Give or take.) Whether it’s worth it is going to be up to the respective owner of a CVO 117”. It’s a big ball park.

Figure 3

Speaking truth to power

What’s obvious is that the Motor Company has provided a way to make up the power deficit existing between sub-700-pound Softails and 840-plus pound Baggers. Since all the factory-backed versions of the M-8 are now “warrantable” and smog legal, I can’t help but wonder why they don’t offer the “real” Screamin’ Eagle versions as a factory option. Whether it’s because they want to allow dealers to make more money, or hold back on giving the most bang up front, or fear such an option would disrupt production if they offered it, or some other unfathomable reason(s)… fact is… they should.

Not every well-heeled connoisseur of things Harley-Davidson just wants looks and gadgets and exclusive paint work. Some, I’d wager, want power… serious power… and are just as willing to put their money where the muscle is. I strongly believe there’s a market for true Screamin’ Eagle bikes.

This head says Screamin’ Eagle, sure enough…but unless it also says “CNC Ported” it ain’t… really!

General Motors found this out in the ’60s and catered to power junkies via the infamous Central Office Production Order (COPO) engine options, often in the plainest, lightest models they made! Just suppose there was a similar Performance Vehicle Operation (PVO?) “system” at the Harley factory. You step into your dealer’s sales office and walk out with a six-to-eight-week wait, while the factory builds you a full-house (Stage IV) machine, complete with factory warranty. For example.

Further suppose they’d do that for you for 40–60 percent less money than it costs to have the dealer do it as an after-the-sale “add-on.” Do you suppose there’s any way you could resist that?

Weighty issues

At the end of the day, no matter how it gets done, if you do it (Stage IV, that is) a lot comes down to the rules and realities of power-to-weight ratios. For instance, our CVO 117” with a stage IV treatment would (pardon the expression) weigh in at about 7 pounds per pony. In terms of torque, the classic Harley advantage, it comes out as 7.3 pounds per ft/lb of the stuff. The even heavier CVO Limited? Well, how’s 7.5 pounds per horse and almost 8 pounds for every increment of torque “twist?”

Now, let’s try it with a Softail, the 656-pound Street Bob. Knowing it will not generate as much power or torque in Stage IV trim as the baggers, we still get only about 5.4 pounds for each horse to haul and the torque-to-weight ratio is also roughly 5:4! What does that tell ya? The bagger has a handicap and it ain’t power. No surprise. But just to rub a little more salt in that wound…we’ll talk about the M-8’s two 114” options… next time.